Fuel injection pump for internal combustion engines

ABSTRACT

In a fuel injection pump of the type wherein the r.p.m. control of the internal combustion engine is effected by throttling to a greater or lesser extent a regulator fluid displaced by a regulator shuttle, there are provided means to vary the largest possible flow passage section for said regulator fluid, in response to shifting gears in said engine, for varying the maximum r.p.m. thereof.

United States Patent [72] Inventors Konrad Eekert Stuttgart-Bad Cannstaat; Franz Eheim, Stuttgart, both 01' Germany [21] Appl. No. 29,114

[22] Filed Apr. 16, I970 [45] Patented Jan. 4, 1972 [73] Assignee Robert Bosch'GmbH Stuttgart, Germany [32] Priority May 2, 1969 [3 3] Germany [54] FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES 7 Claims, 4 Drawing Figs.

[52 us. (:1 74/860, 123/140 FG 511 1111. c1 860k 21/00 [50] Field ofSearch l23/l39. 139.11, 139.11 B, 139.17, 139.18, 140.3; 417/293; 74/860 [56] References Cited UNITED STATES PATENTS 3,403,629 10/1968 Eheim et al. 417/293 3,209,613 10/1965 Potter 74/860 Primary ExaminerLaurence M. Goodridge Att0rney-Edwin E. Greigg ABSTRACT: In a fuel injection pump of the type wherein the r.p.m. control of the internal combustion engine is effected by throttling to a greater or less'er'extent a regulator fluid displaced by a regulator shuttle, there are provided means to vary the largest possible flow passage section for said regulator fluid, in response to shifting gears in said engine, for varying the maximum r.ptm. thereof.

PATENTEUJAN 41972 3631-743 sum 1 [1F 2 INVENTOR. Konrad ECKERT PATENTEUJAN 41972 3631.743

SHEET 2 OF 2 IN VEN TOR.

Konrad ECKER T BY F anz EHE/M FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THE INVENTION This invention relates to a fuel injection pump for internal combustion engines and is of the type wherein the injected fuel quantities may be varied as a function of the r.p.m. by interrupting the delivery of fuel during the pressure strokes of the piston at least upon reaching a maximum r.p.m. Said interruption is effected during the pressure stroke of the pump piston by opening a bypass channel by means of a reciprocating regulator member which is displaced forwardly by a fluid driven by an auxiliary pump operating synchronously with the main pump. The regulator member is braked during its return motion by directing at least one part of the liquid that has caused its forward motion, through at least one arbitrarily variable throttle, so that for a given flow passage section and upon reaching a predetermined r.p.m. the regulator member, by virtue of the appearance of the so-called fluid abutment," does not return into its original position. The maximum possible flow passage section of the aforenoted throttle determines the maximum r.p.m.

In a known fuel injection pump of the aforenoted type (as disclosed in German Pat. No. 1,258,187), the liquid displaced during the return motion of the regulator member is directed through two serially arranged throttles. One of these throttles serves for varying the r.p.m. while the other is preset as the largest possible flow passage section for determining the maximum r.p.m.

When a fuel injection pump of the aforeoutlined type is used in a tractor engine, it is a requirement that the r.p.m. of the engine and thus the maximum speed of the tractor be limited in a variable manner (depending upon local speed limit laws) when the tractor is in gear for street or highway travel. ln lower gears, however, the engine should be able to run at higher r.p.m.s in order to be able to deliver a higher output.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved fuel injection pump which is adapted to comply with the requirements outlined in the preceding paragraph.

Briefly stated, according to the invention, the largest flow passage section determining the maximum r.p.m. during normal operation is changeable, preferably as a function of the gear setting, for varying the maximum possible engine r.p.m.

The invention will be better understood and further objects and advantages of the invention will become more apparent from the ensuing detailed specification of two exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic sectional view of a first embodiment of the invention;

FIG. 2 is a sectional view taken along line II-II of FIG. 1;

FIG. 3 is a fragmentary schematic sectional view of a second embodiment ofthe invention; and

FIG. 4 is a plan view of means securing an electromagnet to the pump housing.

DESCRIPTION OF THE EMBODIMENTS In a pump housing 1 there is provided a cylinder 2 in which operates a pump piston 3. The latter is driven by conventional means, not shown, and is adapted to execute an axial reciprocating motion as well as a rotary motion. Into the cylinder 2 there merge a supply conduit 4 and a determined number of delivery or pressure conduits 5; each of the latter contains a check valve 6. In order to establish connection between the pump work chamber and one of the delivery conduits 5 during each pressure stroke of the piston 3, the latter is provided with a longitudinal distributor groove 7. A longitudinal channel 8, a transversal channel 9, a circumferential annular groove 10, and longitudinally surface grooves 11. all provided in piston 3, periodically establish communication between the supply conduit 4 and the pump work chamber 20 for supplying the latter with fuel from a suction chamber A during the suction strokes of piston 3.

The suction chamber A is supplied with fuel from a tank B by means of a delivery pump C.

For the regulation of the fuel quantity delivered through a pressure conduit 5 of the fuel injection pump during each pressure stroke of pump piston 3, there is provided a regulator shuttle 12 which has two snugly fitting terminal heads 12a and 12b and which operates in a cylinder 13. The regulator shuttle 12 controls a bypass channel formed of two bypass channel portions 14a and 14b. Bypass channel portion 14a connects the pump work chamber 2a with that portion of the cylinder 13 which is bounded by heads 12a and 12b. Bypass channel portion 14b, in turn, establishes communication between cylinder 13 and suction chamber A, where relatively low pressure prevails.

The regulator shuttle 12 is caused to execute forward strokes in response to a periodic force exerted by a regulator fluid which is delivered thereto in a pulsating manner synchronously with the delivery stroke of the pump piston 3. Said fluid is driven by a stepped portion 15 of the piston 3 operating in a cylinder 16. Piston l5 and cylinder 16 thus form an auxiliary pump. The regulator fluid is delivered from cylinder 16 to the terminal face 12c of regulator shuttle 12 through a channel 17 in which there is disposed a check valve 18 preventing fluid flow from the cylinder 13 to cylinder 16 through channel 17. The cylinder 16 is supplied with fuel (regulator fluid) from suction chamber A through a channel 19 opened and closed by the auxiliary piston 15.

The portion of the work cylinder 13 adjacent the face of the regulator shuttle I2, is also connected with cylinder 16 by serially arranged channels 20 and 22 communicating with one another through a cylinder 21. Components 20, 21 and 22 form a return channel means. The channel 20 is throttled at 23 by an oblique control edge 25 of a control plug 24. The flow passage section of throttle 23 is varied by angularly displacing plug 24. The regulator fluid driven by the auxiliary pump 15, 16 causes the regulator shuttle 12 to execute its forward strokes against the force of a return spring 26 which tends to maintain the regulator shuttle 12 in, or return the same into, its initial position in engagement with an abutment 27.

At the moment when, during the pressure stroke of the pump piston 3 and the forward motion of the regulator shuttle 12, the control edge 12d permits communication between the bypass channel portions 14a and 14b, the fuel injection is interrupted. The forward motion of the regulator shuttle 12 is terminated at the moment when the edge 12c opens a port 28 communicating with the suction chamber A through bypass channel portion 14b.

The regulator shuttle 12, during its return stroke, forces regulator liquid from cylinder 13 through throttle 23 into suction chamber A. In this manner the regulator shuttle 12 is braked during its return stroke. Beyond a predetermined r.p.m. of the piston 3, 15, the regulator shuttle 12, because of its aforenoted retarded return motion, is caused to start a forward motion by the immediately following pressure stroke of the piston prior to its return to its position of rest defined by the abutment 27. This phenomenon is the so-called fluid abutment. As a result of the appearance thereof, the distance necessary for the regulator shuttle 12 to travel for opening the bypass channel 14a, 14b, becomes shorter. This distance continues to decrease as the r.p.m. of piston 3, 15 increases while the flow passage section 23 is maintained at the same value. To each setting of the flow passage section 23 thus corresponds a predetermined r.p.m. The smaller the flow passage section 23, the smaller the corresponding r.p.m. since fuel delivery is interrupted relatively early during each pressure stroke of pump piston 3. It is thus seen that the maximum possible flow passage section of the throttle 23 settable by means of the control plug 24, determines the maximum r.p.m.

In the first embodiment depicted in FIGS. 1 and 2, the control plug 24 is provided with a terminal flange 30 which has a radial opening 31. Axially adjacent the flange 30 there is disposed an electromagnet 32, the armature 33 of which is provided with a pin 34 oriented towards the flange 30. When the solenoid 35 is deenergized and the armature 33 assumes its position of rest under the effect of a spring 36, the pin 34 extends into the opening 31 of the flange 30. The armature 33 is prevented from rotating by a pin or abutment 38 which is affixed to the magnetic core 39 and which extends into an opening 37 of armature 33. By means of the cooperation between pin 34 and opening 31, the rotational range of the control plug 24 is limited.

As long as the pin 34 is not in engagement with flange 30 of control plug 24, that is, as long as the solenoid 35 is in an ener gized condition, the throttle 23 may be fully opened by the oblique control edge 25. As soon, however, as the electromagnet 32 is deenergized and thus the spring 36 shifts the armature 33 outwardly, the pin 34 extends into the opening 31 of flange 30. In this manner the angle of rotation of control plug 24 is limited. The opening 31 and the course of the control edge 25 are coordinated in such a manner that when pin 34 projects into opening 31 and thus the angular displacement of the control plug 24 is restricted, the maximum flow passage section allowed at 23 by the control edge 25 is substantially smaller than during the energized condition of the electromagnet 32. As a result, the maximum engine r.p.m. is also substantially smaller.

In case the electromagnet 32 is deenergized at a moment when the pin 34 is not in alignment with the opening 31 and consequently, the pin 34 abuts the frontal face of the flange 30, a small rotation of the control plug 24 in the direction of a smaller r.p.m. suffices to cause the pin 34 to snap into the opening 31 Between the control plug 24 and a setting member 41 operable by the driver, there is disposed a coil spring 42 which transmits a coupling torque from the setting member 41 to the control plug 24. When the pin 34 is in its operative position extending into opening 31, and the driver fully depresses the accelerator, the setting member 41 will tend to rotate the control plug 24 to the maximum extent. The control plug 24, however, is arrested after a limited rotation by pin 34. The setting member 41, on the other hand, continues to rotate, whereupon the coupling spring 42 is tensioned.

The force of the coupling spring 42 is so designed that during normal operation it establishes a clearance-free connection between the setting member 41 and the control plug 24. The spring 42 is disposed about a hollow portion 43 of the setting member 41 and engages with one end a bore 44 of a lug integral with the setting member 41. The other end of spring 42 extends into a bore 45 of a terminal flange 46 integral with the control plug 24. The setting member 41 is rotatably held in a bore of the housing 1 and on a stub 47 which forms part of the control plug 24 and which extends into the hollow portion 43 of the setting member 41.

Turning now to FIG. 3, the second embodiment depicted therein comprises a control plug 24' provided with an axial bore 48 in which there is slidably held a setting piston 49.

The fuel forced through the conduit 22 by the regulator shuttle 12 is admitted to the conduit 20 through an annular groove 50, one boundary of which is formed as an oblique control edge 25 a radial port 51, an annular circumferential groove 52 provided in the setting piston 49, a radial bore 53, and an annular groove 54. The annular grooves 50 and 54, as well as the radial ports 51 and 53, are provided in the cylindrical wall of the control plug 24'. Dependent upon the angular position of the latter, the control edge 25' throttles to a greater or lesser extent the passage 23' through which the conduit 22 opens into the cylinder 21.

The setting piston 49 is fixedly connected with the armature 33 of the electromagnet 32. This arrangement is so designed that when the electromagnet is energized, the setting piston 49 is axially displaced against the force of spring 36 and the flow passage section 59 of the radial port 53 is fully opened. Such a position corresponds to the normal operating conditions.

As the setting piston 49 is displaced axially into its position shown in FIG. 2 upon deenergizing the solenoid 35, the oblique edge 55 narrows the opening 59 of the radial port 53. Thus, the largest possible flow passage section for the regulator liquid is decreased and, as a result, the maximum r.p.m. is also reduced.

The setting piston 49 is provided with an integral terminal flange 56 having a radial cutout 57 into which extends a pin 58 fixedly secured to the magnet core 39. In this manner the setting piston 49 is prevented from angular displacement.

Comparing the aforedescn'bed two embodiments, it is seen that in the structure according to FIGS. 1 and 2, both the normal r.p.m. control (by manipulating setting member 41) and the maximum r.p.m. control (effected by the cooperation between pin 34 and opening 31) occurs at the same throttle 23 by virtue of control edge 25. In the second embodiment (FIG. 3), however, the normal r.p.m. is controlled by the cooperation between the throttle 23' and the control edge 25 of the control plug 24 as the latter is rotated, while the largest possible flow passage section is set by the interaction between the throttle 59 and the control edge 55 of the setting piston 49.

In both embodiments, the deenergization of the solenoid 35 occurs when the tractor engine is put into a gear corresponding to the highest tractor speed. By virtue of the decreased flow passage sections 23 (FIG. 1) and 59 (FIG. 3), the r.p.m. of the engine and thereby the highest tractor speed may be decreased to comply with the legal speed limits.

The largest possible flow passage section 23, 59, which determines the maximum r.p.m. and which becomes effective when the electromagnet 32 is deenergized, may be preset in both embodiments by turning the entire electromagnet 32 in the pump housing 1. For this purpose, as shown in FIG. 4, there are provided slots 61 in the flange 60 of the housing of the electromagnet 32. The electromagnet may be rotated upon temporarily loosening the tightening screws 62. In the first embodiment, upon turning the electromagnet 32, the position of the pin 34 varies with respect to the opening 31, whereas in the second embodiment, the position of the oblique control edge 55 varies with respect to the radial port 53.

That which is claimed is:

1. In a fuel injection pump associated with an internal combustion engine, the improvement comprising A. a first cylinder,

B. a pump piston slidably disposed in said first cylinder and defining therewith a pump work chamber,

C. means for reciprocating said pump piston,

D. pressure conduit means communicating with said pump work chamber to carry fuel pressurized in said pump work chamber by each pressure stroke of said pump piston,

E. a second cylinder,

F. an auxiliary piston slidably disposed in said second cylinder,

G. means to operate said auxiliary piston synchronously with said pump piston,

H. a third cylinder,

1. a regulator shuttle slidably disposed in said third cylinder and having a work face,

J. a channel connecting said second cylinder with said third cylinder to carry to said work face liquid pressurized by each pressure stroke of said auxiliary piston for causing said regulator shuttle to execute forward strokes,

K. check valve means disposed in said channel for permitting the flow of liquid therein from said second cylinder to said third cylinder and preventing the flow of liquid therein from said third cylinder to said second cylinder,

L. means for exerting a force on said regulator shuttle for causing the latter to execute return strokes during the suction strokes of said pump piston and said auxiliary piston,

M. a bypass channel communicating with said pump work chamber and with said third cylinder, said bypass channel being opened by said regulator shuttle during the reciprocation thereof to interrupt the delivery of fuel through said pressure conduit means,

N. return channel means communicating with said third cylinder adjacent the work face of said regulator shuttle for carrying the liquid displaced by said work face of said regulator shuttle during the return strokes thereof,

0. throttle means disposed in said return channel means to brake the flow of liquid therein for reducing the speed of said regulator shuttle during its return strokes and for generating, beyond a predetermined speed of said pump piston and said auxiliary piston, a fluid abutment in said third cylinder adjacent said work face, said fluid abutment preventing said regulator shuttle from returning to its initial position of rest, said throttle means including 1. control plug means in a unitary structure having control edge means cooperating with said return channel means to determine the fiow passage section thereof,

2. arbitrarily operable means to move said control plug means for varying said flow passage section up to a maximum value and P. electromagnetic means associated with said control plug means for changing, dependent upon the condition of energization of said electromagnetic means, said maximum value ofsaid flow passage section.

2. An improvement as defined in claim 1, wherein the energization and deenergization of said electromagnetic means is controlled by the shifting of transmission gears associated with said engine.

3. An improvement as defined in claim 1, wherein said electromagnetic means includes an abutment adapted to assume a first position and a second position; when in said first position, said abutment is spaced from the path of motion of said control plug means permitting the latter to vary said flow passage section in response to said arbitrarily operable means, up to a first maximum value; when in said second position, said abutment is in the path of motion of said control plug means permitting the latter to vary said flow passage section in response to said arbitrarily operable means, up to a second maximum value which is smaller than said first maximum value.

4. An improvement as defined in claim 3, including a coupling spring establishing connection between said arbitrarily variable means and said control means.

5. An improvement as defined in claim 3, wherein said control plug means varies said flow passage section by rotation; said abutment, when in said second position, limits the range of rotation of said control means.

6. An improvement as defined in claim 5, wherein said control plug means has an integral flange provided with an opening, said abutment is formed of a pin which, in said first position, is withdrawn from said opening and, in said second position, projects thereinto.

7. An improvement as defined in claim 1, wherein said control plug means includes A. a rotatable control plug connected to said arbitrarily operable means and having 1. an axial bore,

2. a control edge for determining said flow passage section as a function of said arbitrarily operable means,

3. a radial port communicating with said axial bore and forming part of said return channel means and B. an axially slidable setting piston disposed in said axial bore of said rotatable control plug and having a control edge cooperating with said radial port to determine the flow passage section thereof, the magnitude of the lastnamed flow passage section constituting said maximum value, said setting piston being connected to said electromagnetic means to be shifted thereby as a function of its condition of energization. 

1. In a fuel injection pump associated with an internal combustion engine, the improvement comprising A. a first cylinder, B. a pump piston slidably disposed in said first cylinder and defining therewith a pump work chamber, C. means for reciprocating said pump piston, D. pressure conduit means communicating with said pump work chamber to carry fuel pressurized in said pump work chamber by each pressure stroke of said pump piston, E. a second cylinder, F. an auxiliary piston slidably disposed in said second cylinder, G. means to operate said auxiliary piston synchronously with said pump piston, H. a third cylinder, I. a regulator shuttle slidably disposed in said third cylinder and having a work face, J. a channel connecting said second cylinder with said third cylinder to carry to said work face liquid pressurized by each pressure stroke of said auxiliary piston for causing said regulator shuttle to execute forward strokes, K. check valve means disposed in said channel for permitting the flow of liquid therein from said second cylinder to said third cylinder and preventing the flow of liquid therein from said third cylinder to said second cylinder, L. means for exerting a force on said regulator shuttle for causing the latter to execute return strokes during the suction strokes of said pump piston and said auxiliary piston, M. a bypass channel communicating with said pump work chamber and with said third cylinder, said bypass channel being opened by said regulator shuttle during the reciprocation thereof to interrupt the delivery of fuel through said pressure conduit means, N. return channel means communicating with said third cylinder adjacent the work face of said regulator shuttle for carrying the liquid displaced by said work face of said regulator shuttle during the return strokes thereof, O. throttle means disposed in said return channel means to brake the flow of liquid therein for reducing the speed of said regulator shuttle during its return strokes and for generating, beyond a predetermined speed of said pump piston and said auxiliary piston, a fluid abutment in said third cylinder adjacent said work face, said fluid abutment preventing said regulator shuttle from returning to its initial position of rest, said throttle means including
 1. control plug means in a unitary structure having control edge means cooperating with said return channel means to determine the flow passage section thereof,
 2. arbitrarily operable means to move said control plug means for varying said flow passage section up to a maximum value and P. electromagnetic means associated with said control plug means for changing, dependent upon the condition of energization of said electromagnetic means, said maximum value of said flow passage section.
 2. arbitrarily operable means to move said control plug means for varying said flow passage section up to a maximum value and P. electromagnetic means associated with said control plug means for changing, dependent upon the condition of energization of said electromagnetic means, said maximum value of said flow passage section.
 2. An improvement as defined in claim 1, wherein the energization and deenergization of said electromagnetic means is controlled by the shifting of transmission gears associated with said engine.
 2. a control edge for determining said flow passage section as a function of said arbitrarily operable means,
 3. a radial port communicating with said axial bore and forming part of said return channel means and B. an axially slidable setting piston disposed in said axial bore of said rotatable control plug and having a control edge cooperating with said radial port to determine the flow passage section thereof, the magnitude of the last-named flow passage section constituting said maximum value, said setting piston being connected to said electromagnetic means to be shifted thereby as a function of its condition of energization.
 3. An improvement as defined in claim 1, wherein said electromagnetic means includes an abutment adapted to assume a first position and a second position; when in said first position, said abutment is spaced from the path of motion of said control plug means permitting the latter to vary said flow passage section in response to said arbitrarily operable means, up to a first maximum value; when in said second position, said abutment is in the path of motion of said control plug means permitting the latter to vary said flow passage section in response to said arbitrarily operable means, up to a second maximum value which is smaller than said first maximum value.
 4. An improvement as defined in claim 3, including a coupling spring establishing connection between said arbitrarily variable means and said control plug means.
 5. An improvement as defined in claim 3, wherein said control plug means varies said flow passage section by rotation; said abutment, when in said second position, limits the range of rotation of said control plug means.
 6. An improvement as defined in claim 5, wherein said control plug means has an iNtegral flange provided with an opening, said abutment is formed of a pin which, in said first position, is withdrawn from said opening and, in said second position, projects thereinto.
 7. An improvement as defined in claim 1, wherein said control plug means includes A. a rotatable control plug connected to said arbitrarily operable means and having 